The School of Arts & Sciences

Department of Natural Sciences

Roy Khalaf

After obtaining his BS in Biology from Haigazian University in Lebanon in 1993, Dr. Roy Khalaf left for the United States to pursue his higher education. In 1995, he joined the Department of Biology of the State University of New York at Albany as a Master’s student. Six years later, and under the supervision of Dr. Richard Zitomer, Dr. Khalaf graduated with an MS and a PhD in Molecular Biology. He then decided to continue his learning experience and joined the lab of Dr. William Fonzi at the Georgetown University Medical Center in Washington DC as a postdoctoral research fellow. He remained there for one year, then returned to Lebanon where he is currently associate professor of molecular biology at the Lebanese American University. 

Dr. Khalaf’s main research interests revolve around the opportunistic human fungal pathogen, Candida albicans. C. albicans is one of the major causative agents of death in immunocompromised individuals. Through the use of the latest techniques in molecular biology, Dr. Khalaf’s lab is trying to identify and characterize novel cell wall proteins that are involved in the virulence and pathogenicity of this organism through generating genetically engineered knock out strains and assessing their impact on virulence, filamentation, adhesion, biofilm formation and cell wall proteome architecture through MALDI-TOF mass spectrometry. Furthermore, the lab is also in the process of genotyping drug resistant and drug sensitive C. albicans isolated from Lebanese hospital patients by sequencing, in an effort to understand the molecular basis of resistance, and eventually improve the treatment of candidiasis and patient well-being.

In addition, and through collaborative efforts with the School of medicine at LAU, Dr. Khalaf is involved in a project that involves identifying and characterizing putative prions in the yeast Saccharomyces cerevisiae.

Publications

  1. Deckert J, Khalaf RA, Hwang SM, and Zitomer RS. Characterization of the DNA binding and bending HMG domain of the yeast hypoxic repressor Rox1. Nucleic Acids Research 1999; 27(17): 3518-26.
  2. Khalaf RA, and Zitomer RS. The DNA binding protein Rfg1 is a repressor of filamentation in Candida albicans. Genetics 2001;157 (4):1503-12.
  3. Limijindaporn T, Khalaf RA, and Fonzi WA. Nitrogen metabolism and virulence of Candida albicans requires the GATA-type transcriptional activator encoded by GAT1. Molecular Microbiology 2003;50 (3), 993-1004.
  4. Yazbek S, Barada G, Basma R, and Khalaf RA. Significant discrepancy between Real Time PCR identification and hospital identification of C. albicans isolates from Lebanese hospital patients. Medical Science Monitor 2007. 13(5); MT7-12.
  5. Barada G, R. Basma R, and Khalaf RA. Candida albicans Identification and Genotyping in Lebanese Clinical Isolates Through Microsatellite DNA Polymorphism. Mycopathologia 2008;165(3):115-25.
  6. Dib L, Hayek P, Sadik H, Beyrouthy B, and Khalaf RA. The Candida albicans Ddr48 Stress Response Protein is Essential for Filamentation, Virulence, and Confers Partial Antifungal Drug Resistance. Medical Science Monitor 2008;14 (6):BR113-121.
  7. Basma R, Barada G, Ojaimi N, Khalaf RA. Susceptibility of Candida albicans to common and novel antifungal drugs, and relationship between the mating type locus and resistance, in Lebanese hospital isolates. Mycoses. 2009, 52(2):141-8.
  8. Bitar M, Khalaf R, Sabbagh A, Shamseddine W, El Hajj N, Zaatari G, Fuleihan N, Greige L, Mahfouz R Killer Cell Immunoglobulin-like Receptor (KIR) Genotypes in patients with recurrent tonsillitis. Genetic Testing and Molecular Biomarkers. 2008, 12(4):517-521
  9. Mahfouz R, Sabbagh S.A, Khazen G, El Hajj N, Rayes R, Arayssi TK, Zaatari G.S, Khalaf R.A. Distribution of Killer Cell Immunoglobulin-like Receptor (KIR) Genotypes in Patients with Familial Mediterranean Fever. Genetic Testing and Molecular Biomarkers. 2009, 13(1): 91-95
  10. Hayek P, Dib L, Yazbeck P, Beyrouthy B, Khalaf RA. Characterization of Hwp2, a Candida albicans GPI anchored cell wall protein necessary for invasive growth. Microbiological Research 2010 Mar 31;165(3):250-8
  11. Ramsook C, Tan C, Garcia MC, Fung R, Soybelman G, Henry R, Litewka A, O’Meally S, Otoo H.N, Khalaf R.A, Dranginis A, Gaur N.K, Klotz S.A, Rauceo JM, Jue C.K, Lipke P.N. Yeast Cell Adhesion Molecules Have Functional Amyloid Forming Sequences. Eukaryotic Cell 2010 Mar;9(3):393-404.
  12. Hashash R, Younes S, Bahnan W, El Koussa J, Maalouf K, Khalaf RA. Characterization of Pga1, a Candida albicans Cell Wall Protein necessary for proper adhesion and biofilm formation. Mycoses. 2011 Nov;54(6):491-500
  13. Younes S, Bahnan W, Khalaf RA. The Candida albicans Hwp2 is necessary for proper adhesion, biofilm formation and oxidative stress tolerance Microbiological Research. 2011 Jul 20;166(5):430-6
  14. Daher J, Younes S, Koussa J, Khalaf RA. Characterization of Dse1, a Candida albicans essential cell wall protein. Interdisciplinary Perspectives on Infectious Diseases. 2011;2011:504280.
  15. Bahnan W, Koussa J, Younes S, Abi Rizk , Khalil B, El Sitt S, Hanna S, El Sibai M, Khalaf R.A. Deletion of the Candida albicans PIR32 results in increased virulence, stress response, and upregulation of cell wall chitin deposition. Mycopathologia. 2012 Aug;174(2):107-19
  16. Younes S.S, Khalaf RA. The Candida albicans Hwp2p can complement the lack of filamentation of a Saccharomyces cerevisiae muc1 null strain. Microbiology. 2013 Jun;159(Pt 6):1160-4.
  17. Khalaf R, Hoteit R, Yazbek S, El Hajj N, Otrock Z, Khansa S, Sabbagh A, Shammaa D, Mahfouz RA. Natural Killer Cell Immunoglobulin-like Receptors (KIR) Genotypes in Follicular Lymphoma patients: Results of a pilot study.Gene. 2013 Aug 1;525(1):136-40.
  18. Bitar I1, Khalaf RA1, Harastani H, Tokajian S. Identification, Typing, Antifungal Resistance Profile, and Biofilm Formation of Candida albicans Isolates from Lebanese Hospital Patients. 1 Both authors contributed equally to the work. Biomed Res Int. 2014;2014:931372.
  19. Zohbi R, Wex B, Khalaf RA. Comparative proteomic analysis of a Candida albicans DSE1 mutant under filamentous and non-filamentous conditions. Yeast. 2014 Nov;31(11):441-8.
  20. Awad A. El Khoury P, Wex B. Khalaf RA. Proteomic Analysis of a Candida albicans pga1 Null Strain. EuPa Open Proteomics. 2018 Feb 22;18:1-6. doi: 10.1016/j.euprot.2018.02.001. eCollection 2018 Jun.
  21. El Khoury P, Awad A, Wex B, Khalaf RA. Proteomic analysis of a Candida albicans pir32 null strain reveals proteins involved in adhesion, filamentation and virulence. PLoS One. 2018 Mar19;13(3):e0194403. doi:10.1371/journal.pone.0194403. eCollection 2018.
  22. Awad A, El Khoury P, Wex B, Khalaf RA. Tandem Mass Spectrometric Cell Wall Proteome Profiling of a Candida albicans hwp2 Mutant Strain. Curr Mol Pharmacol. 2018;11(3):211-225. doi: 10.2174/1874467211666180509153228.
  23. El Khoury P, Salameh C,  Awad A. Said Y, Khalaf RA. Phenotypic and proteomic characterization of Ddr48, a Candida albicans cell wall protein. Submitted to Medical mycology-under review.
  24. Toutounji M, Tokajian ST, Khalaf RA. Genotypic and phenotypic characterization of Candida albicans Lebanese hospital isolates resistant and sensitive to capofungin. Submitted to Fungal Genetics and Molecular Biology -under review.

Academic degrees

 


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